This invention is generally directed to imaging members, and, more specifically, the present invention is directed to multilayered photoconductive imaging members with a solvent resistant hole blocking and electron transporting and/or partially conducting layer comprised of a thick film, for example, from about 0.05 to about 5 and preferably from about 1 to about 3 microns of a component obtained from a solution of a hydroxy containing polymer, copolymer, terpolymer, or mixtures thereof of, for example, polyhydroxyalkyl acrylate or polyhydroxyalkyl methacrylate, and more specifically poly(2-hydroxyethyl acrylate), poly(2-hydroxyethyl methacrylate), poly(3-hydroxypropyl acrylate), poly(4-hydroxybutyl acrylate), and the like, and an aminoalkylalkoxysilane, such as 3- or gamma-aminoalkyltrialkyloxysilane. This layer or film is easily coatable, thus print defects can be eliminated or minimized; is substantially free of dielectric breakdown in bias charging roll development systems, as compared, for example, to a single layer of gamma-aminopropyltrimethoxysilanes, and which silanes are difficult to coat uniformly as thin films, thus causing print defects, are susceptible to dielectric breakdown with bias roll development systems, and wherein any uncured silane contaminates the photogenerating layer and thereby changes the photoconductor device photosensitivity and adversely affects the cyclic stability in different atmospheres. Additionally, the gamma silane is susceptible to cracking primarily because of the high crosslink density thereof, which disadvantages can be avoided or minimized with the photoconductive members of the present invention. Moreover, thin silane layers (less than 500 Angstroms) may leave unwetted areas during the coating process. Thick undercoat layers of, for example, from about 1 to about 10 microns provide for improved coating uniformity, and the use of inexpensive substrates because substrate defects can be covered up (or masked), resulting in improved print quality as substrate defects are not printed out in the developed copies produced. Moreover, a thick undercoat layer as compared to a thin, less than 500 Angstroms, for example from about 200 to about 400 Angstroms, enables better electrical properties by preventing or minimizing the injection of holes into the photogenerator layer while allowing electron transport from the photogenerator layer to the ground plane after light exposure. Whether thick or thin, it is important that the undercoat possesses environmental insensitivity to changes in temperature and relative humidity; enables low residual voltages and dark decay voltages, and allows cyclic stability for more than 100,000 cycles. The undercoating layer is preferably in contact with the supporting substrate and is preferably situated between the supporting substrate and the photogenerating layer, and which layer may be comprised of the photogenerating pigments of U.S. Pat. No. 5,482,811, the disclosure of which is totally incorporated herein by reference, especially Type V hydroxygallium phthalocyanine, halogallium phthalocyanine, dimers generated from the reaction of HOGaPc and CIGaPc, bisimidazoleperylene, trigonal selenium, metal free x-phthalocyanine and metal containing phthalocyanines, such as vanadyl phthalocyanine, mixtures thereof, and the like.
The imaging members of the present invention in embodiments exhibit excellent cyclic/environmental stability, independent layer discharge, and substantially no adverse changes in performance over extended cyclic time periods, and wherein the imaging members, such as photoconductive members, also possess solvent resistant blocking layers, and enable suitable hole blocking layer thickness that can be easily coated on the supporting substrate by various coating techniques of, for example, dip or slot-coating. The aforementioned photoresponsive, or photoconductive imaging members can be negatively charged when the photogenerating layer is situated between the hole transport layer and the blocking layer deposited on the substrate. The invention imaging members are in embodiments sensitive in the wavelength region of, for example, from about 550 to about 900 nanometers, and in particular, from about 650 to about 850 nanometers, thus diode lasers can be selected as the light source.
Processes of imaging, especially xerographic imaging and printing, including digital, are also encompassed by the present invention. More specifically, the layered photoconductive imaging members of the present invention can be selected for a number of different known imaging and printing processes including, for example, multifunctional imaging/facsimile devices electrophotographic imaging processes, especially xerographic imaging and printing processes wherein charged latent images are rendered visible with toner compositions of an appropriate charge polarity. Moreover, the imaging members of the present invention are preferably useful in color xerographic applications where several color printings can be achieved in a single pass.